1. Field of the Invention
The present invention relates to a manufacturing method of an array substrate and a manufacturing method of a liquid crystal display device using the same, and particularly to a manufacturing method of an array substrate used for a reflective or transflective liquid crystal display device and a manufacturing method of a liquid crystal display device using the same.
2. Description of Related Art
An array substrate such as a thin film transistor (TFT) substrate is generally fabricated by repeating a process as described below. First, a conductive thin film and an insulating thin film are formed on an insulating substrate by using a sputtering method, a CVD method or the like. Next, a photoresist coated on the whole surface of the formed thin film to form a resist layer, is exposed to light through a specified photomask and is developed, so that a resist pattern having a specified shape is formed. Next, the thin film is etched while using the resist pattern as an etching mask, and the thin film having the specified shape is formed, and then, the resist pattern is peeled off.
In recent years, with the improvement in the resolution of a liquid crystal display device, it becomes necessary to increase the thickness of wiring and to improve the aperture ratio of a pixel. Thus, as a protection film formed on a TFT, not a silicon nitride (SiN) film or the like, but an organic insulating film which can be formed by using a spin coat method or the like has been often used. Since the organic insulating film is easy to be formed into a relatively thick film, a stepped portion formed by the increase in the thickness of the wiring can be flattened. Besides, when the organic insulating film is formed into the thick film, parasitic capacitance Cds formed between a pixel electrode and a drain bus line can be reduced, and therefore, it becomes possible to improve the aperture ratio of the pixel.
In the reflective or transflective liquid crystal display device, there is a structure in which irregularities are formed on the surface of a reflecting electrode, and incident light is scattered and reflected to improve reflection display characteristics. The irregularities of the reflecting electrode are formed by providing irregularities on the surface of the organic insulating film of the lower layer by using various methods. The irregularities of the surface of the organic insulating film are sometimes formed with irregular shapes in the respective pixels. At a later process after the irregularities are formed on the surface of the organic insulating film, for example, even if a defect such as a short circuit between reflecting electrodes occurs, an optical inspection for optically detecting defects by pattern comparison is difficult to carry out. Thus, conventionally, after the TFT substrate is completed, a tester is used to specify an address of a short circuit defect, and the short circuit part is cut by laser repair or the like to repair the defect. Originally, although only the layer of the reflecting electrode in which the short circuit defect occurs has only to be repaired, there is a case where especially in the TFT substrate with a high aperture ratio, another wiring line, such as a drain bus line, overlapping with the short circuit part is also cut. Accordingly, since dot defects and the like are increased, and the number of repair steps is increased, there occurs a problem that the display quality of the liquid crystal display device is lowered, and the manufacturing cost is increased.